The world's most popular sport is under investigation for corruption. European police say they've found evidence of a vast criminal network that fixed hundreds of soccer matches. The conspiracies are alleged to span continents and involve players, team officials, league staff and serious criminals. Investigators say they're looking at teams competing for places in soccer's biggest tournament, the World Cup.

NPR's London correspondent Philip Reeves is covering this story. Philip, good morning.

PHILIP REEVES, BYLINE: Good morning.

INSKEEP: So how bad is it?

REEVES: It is very serious, indeed. This is the result of an investigation by the European law enforcement agency, Europol, in cooperation with other forces. Europol has identified more than 680 games around the world suspected of being fixed. Three hundred and eighty of these were in Europe. Some of these were pretty lowly fixes, frankly. But some involved in the sport's most prestigious tournament, international matches and many of them including qualifiers for the World Cup and European championship, and several champions league games, and some top-flight domestic league matches, too.

INSKEEP: So, according to the investigators, how did the fixing work? Were players paid to lose? What do they do?

REEVES: Well, it's not entirely clear how the fixing works in practice. And then remember that people don't just bet on the outcome of a game these days. They bet on whether there will be a red card. They bet on whether there'll be a penalty. They bet on who might score. So there are lots of ways of doing it.

INSKEEP: It gives a whole new beauty to the phrase: Bend it like Beckham. But are these teams that American might be familiar with?

REEVES: Well, they haven't identified the games or the people involved. They say - Interpol says - that 425 match and club officials, players and, of course, criminals are involved in 15 countries. But it's not clear, you know, what these numbers exactly refer to and whether they include incidents of match fixing that have already come to light. There've been plenty of these is in recent times, some of which have led to convictions.

A bunch of people are doing jail time in Germany, for example. There've been two huge and match-rigging scandals in Italy in the last seven years. And not so long ago there was a scandal in Turkey over two rather obscure international matches, in which all seven goals were the result of penalties. For those unfamiliar with his fabulous sport, that's very unusual, indeed. And the refs in those games and ended up being banned from officiating.

INSKEEP: Phil, as you talk, I'm reminded of cycling, where there were suspicions and allegations of doping for many years before it burst fully to the surface. It sounds like that's the case here. Did people like you who closely follow this sport have some idea that this was a problem for a long time?

REEVES: Oh yes, these betting syndicates have been to been around for a long time. And, you know, they're like a giant multinational corporations. They blighted other sports apart from soccer, including cricket. Vast amounts of money involved, a lot of that does come from soccer.

You know, it's an activity that tends to attract organized crime, as it's considered less risky and easier than other rackets, like trafficking drugs, for example.

INSKEEP: So what does this mean for the sport?

REEVES: It means soccer is going to have to clean up its act and pretty fast. Europol's director says the very fabric of the sport threatened. And as you said, it's the world's most popular sport. It generates fortunes. It generates great passions amongst its fans. It's drenched with history and tradition. A loss of faith in the sport could be very damaging.

So, the sports authorities are trying. They've been trying to combat the betting syndicates for a while, actually. For example, FIFA, the world governing body of soccer, has set up an early warning system to monitor betting. But it is clear a lot more action is going to be necessary.